It is desirable to produce rubber compounds exhibiting reduced hysteresis when properly compounded with other ingredients such as reinforcing agents, followed by vulcanization. The hysteresis of a rubber compound refers to the difference between the energy applied to deform an article made from the rubber compound and the energy released as the rubber compound returns to its initial, undeformed state. In pneumatic tires, lowered hysteresis properties are associated with reduced rolling resistance and heat build-up during operation of the tire. These properties, in turn, result in such desirable characteristics as lowered fuel consumption of vehicles using such tires.
Precipitated silica has been increasingly used as a reinforcing particulate filler in rubber components of tires and mechanical goods. The reason silica is used in tires is to improve the performance balance between wet traction and rolling resistance, snow/ice traction and, mechanical properties, such as wear performance. Silica-loaded rubber stocks, however, have heretofore exhibited relatively poor resilience and high compound viscosity when used without any silane-coupling agent, which is somewhat expensive to be widely used in the industry. Even with a certain amount of silane-coupling agent, total balance of the foregoing performances was often not sufficient.
To that end, to alter or manipulate the properties of rubbery polymers, and thus the characteristics of a tire utilizing such rubbery polymer, various functional groups can be incorporated into the rubbery polymer for desirably interacting with reinforcing filler and conceivably reducing the amount of expensive silane-coupling agent. Unfortunately, due to the unpredictable interactions of the various compounds and chemicals used for synthesizing and compounding these rubbery polymers, it can be challenging to formulate useful functionalized rubber compounds that provide tires with overall desirable performance characteristics.
It is thus desirable to provide a process for synthesizing rubbery polymers that are alkoxy functionalized, wherein the rubbery polymers provide desirable dispersion of silica in rubber compounds and desirable wear properties.